STRUCTURAL STUDIES OF NUCLEOTIDE DEPENDENT ENZYMES

描述：核苷酸在几乎所有的 它们提供DNA和RNA的构建模块的生化过程， 在各种代谢途径中充当能量货币， 酶活性调节剂，并作为瞬时电子 接受者和捐赠者。这项研究计划的目的是 了解，在分子水平上，核苷酸在整体中的作用 四种蛋白质系统的催化机制：乙酰辅酶A羧化酶 它是Mg（II）-ATP依赖性的，卡那霉素核苷酸转移酶， 使用ATP、GTP或UTP作为底物，UDP-半乳糖4-差向异构酶， 需要紧密结合的NAD的活性，和L-苯丙氨酸脱氢酶 其可逆地结合NAD或NADH。 卡那霉素核苷酸转移酶催化各种 氨基糖苷类抗生素常用于治疗严重的 需氧革兰氏阴性菌感染。 UDP-半乳糖4- 差向异构酶在适当的半乳糖代谢中起关键作用，事实上， 半乳糖血症的一种形式是由这种酶的缺乏引起的。 乙酰coa 羧化酶催化的第一个和绝对关键的步骤， 长链脂肪酸的生物合成。 最后，L-苯丙氨酸 脱氢酶催化L-苯丙氨酸的氧化脱氨基。 对于拟议的研究，定点诱变，x- 射线晶体学和动力学测量将被采用。 采取 总之，这些研究将提供一个详细描述的作用， 这些蛋白质的酶功能中的核苷酸。

DESCRIPTION: Nucleotides serve important roles in virtually all biochemical processes where they provide building blocks for DNA and RNA, act as currencies of energy in various metabolic pathways, serve as modulators of enzymatic activity, and function as transient electron acceptors and donors. The objective of this research program is to understand, on a molecular level, the role of nucleotides in the overall catalytic mechanisms of four protein systems: acetyl-CoA carboxylase which is Mg(II)-ATP dependent, kanamycin nucleotidyltransferase which can employ ATP, GTP, or UTP as a substrate, UDP-galactose 4-epimerase which requires tightly bound NAD for activity, and L-phenylalanine dehydrogenase which binds NAD or NADH reversibly. Kanamycin nucleotidyltransferase catalyzes the inactivation of various aminoglycoside antibiotics often employed in the treatment of serious infections due to aerobic Gram-negative bacteria. UDP-galactose 4- epimerase plays a key role in proper galactose metabolism, and indeed, one form of galactosemia arises from a deficiency in this enzyme. Acetyl-CoA carboxylase catalyses the first and absolutely critical step in the biosynthesis of long chain fatty acids. Finally, L-phenylalanine dehydrogenase catalyzes the oxidative deamination of L-phenylalanine. For the proposed studies, a combination of site-directed mutagenesis, x- ray crystallography, and kinetic measurements will be employed. Taken together, these studies will provide a detailed description of the role of nucleotides in the enzymatic functions of these proteins.